The invention relates to an elastic composite material for making elastic sides of diapers and of elastic diaper closure tapes, with an elastic substrate that can preferably stretch in one direction and with at least one textile outer layer consisting of a knit fabric. In order to ensure a good fitting shape of the diaper, elastic sides in diapers or elastic diaper closure tapes must have high elasticity and be able to stretch by more than 20 mm for the cited applications. Since they can come in contact with the body, they should be air permeable and have a soft textile surface. Finally, a high resistance to tearing of the elastic composite material is required for the cited applications.
U.S. Pat. No. 5,762,623 teaches a composite material comprising a first textile outer layer of a knit fabric, a second outer layer of spun fabric and an elastic substrate as core. The substrate consists of individual elastic threads extending in the high-stretch direction of the composite material. The threads are embedded in a suitable binder that fills out the space between the threads and also partially penetrates the outer textile layers. The binder is not air-permeable and therefore does not meet an important criterion for the previously cited applications.
US 2004/0214494 describes a composite material for diapers that comprises textile outer layers as well as an elastic core consisting of two layers. The outer layers can consist of a knit fabric. The core also comprises a layer of a knit fabric as well as comprises elastic threads extending in the high-stretch direction of the material. The elastic threads are cast in a suitable binder that fills out the hollow spaces between the outer layers and also partially permeates the outer layers. The textile layer of the core is intended to improve the composite strength and the adhesion between the individual layers. The elastic threads are cast in the binder in the extended state. The compound material is also not permeable to air.
U.S. Pat. No. 4,705,710 teaches a biaxially stretchable composite material with knitted-in loops that can be used as part of a Velcro strip fastener. The knit fabric comprises elements of an elastically stretchable material and is applied on an elastic substrate. Due to its biaxial stretchability the material is not suitable for the production of elastic sides for diapers or for the production of elastic diaper closure tapes because a composite material is required for these applications that can be stretched uniaxially and is relatively stiff transversely to the high-stretch direction so that the material does not contract transversely to the stretch direction upon a longitudinal expansion.